One type of ink-jet printing system has a printhead mounted to a carriage that is moved back and forth over print media, such as paper. As the printhead passes over appropriate locations on the print media, a control system activates the printhead to eject ink drops onto the print media and form desired images and characters. To work properly, such printing systems must have a reliable supply of ink for the printhead.
One category of ink-jet printing system uses an ink supply that is mounted to and moves with the carriage. In some types, the ink supply is replaceable separately from the printhead. In others, the printhead and ink supply together form an integral unit that is replaced once the ink in the ink supply is depleted.
Another category of printing system uses ink supplies that are not located on the carriage. One type replenishes the printhead intermittently. The printhead will travel to a stationary reservoir periodically for replenishment. Another type, referred to as a replaceable off-axis ink supply, has a replaceable ink cartridge or container connected to the printhead by a fluid conduit. The ink cartridge has a fluid reservoir filled with ink and located within a housing. The reservoir has a fluid coupling mechanism for coupling the reservoir to the printing system so that ink may flow from the reservoir to the printhead. The reservoir is sometimes pressurized in some manner to provide a reliable high flow rate supply of ink to the printhead.
In the parent application to this U.S. patent application, Ser. No. 08/785,580, U.S. Pat. No. 5,812,156 a replaceable off-axis cartridge is described which has a memory device mounted to the housing. When inserted into the printing system station, an electrical connection between the printing system and the memory device is established. This electrical connection allows for the exchange of information between the printing system and the memory. The memory device stores information that is utilized by the printing system to ensure high print quality. This information is provided to the printing system automatically when the cartridge is mounted to the printing system. The exchange of information assures compatibility of the cartridge with the printing system. The stored information includes helpful information, such as the date when the cartridge was first installed on a printing system. This installation date indicates whether the ink is out of date and thus losing quality.
Another use for the memory device discussed in Ser. No. 08/785,580 U.S. Pat. No. 5,812,156 is to prevent the use of the cartridge after the supply of ink is depleted. Operating a printing system when the reservoir has been depleted of ink can destroy the printhead. The memory devices concerned with this application are updated with data from the printing system concerning the amount of ink left in the reservoir as it is being used. When a new cartridge is installed, the printing system will read information from the memory device indicative of the reservoir volume. During usage, the printing system estimates ink usage and updates the memory device to indicate how much ink is left in the cartridge. When the ink is substantially depleted, this type of memory device can store data indicative of an out of ink condition. When substantially depleted of ink, these cartridges are typically discarded and a new cartridge along with a new memory device is installed.
After being depleted of ink, the cartridges are potentially capable of further use if replenished with a fresh supply of ink. However, these cartridges are designed for single use because of the information stored in the memory device that indicates the amount of ink that was in the reservoir prior to being refilled. If refilled and installed again on a printing system, the data in the memory would still indicate the volume of ink that it contained prior to refilling. The data would still indicate the initial installation date, not the date when it was re-installed on a printing system. The low ink warning which the memory would signal would not be meaningful to the user because it would be inaccurate. The user would be deprived of the numerous advantages and safeguards of the memory device. As a result, the reservoir is not designed for refilling.